The present invention relates primarily to rotary lawn mowers, and particularly to rotary mowers including means for adjusting their rotary knife blades to various cutting widths. The mower also includes a re-cutting element in addition to the primary cutting means. The new adjustable mower and knife blades assembly replaces the need for a large number of single component, conventional knife blade designs and sizes.
Due to the equal upward and downward angularity of the knife sections relative to the straight knife center portion, the cutting edges can be re-sharpened by firmly holding the angled end faces against a straight grinding surface in two set-ups for each knife blade. The new mower arm and knife blades assembly will have particular appeal to the lawn maintenance contractor whose single edged knife blades require re-sharpening at least once every week. Using the new, replaceable, twin-edged knife blade will either eliminate or greatly reduce re-sharpening with attendant time and cost factors. This is a significant advantage since sharpening is generally preferred over discarding the dull knives. Also, the majority of large size mowers do not mulch the grass clippings, which requires extra time for raking and removal. This invention recuts the grass into a suitable mulch.
The new mower arm is considerably stiffened by its outside flanges, which results in a reduction in material width, thickness and weight of both the mower arm and matching knife blades. The mower arm is also provided with the largest popular pivot center hole size. An additional set of snugly fitting center hole washers with a variety of concentric bore sizes will fit the mower arm to the vast majority of drive spindle adapter stud and bolt sizes. This adaptability is a further advantage of the invention.